1. Technical Field
Example embodiments relate to semiconductor memory devices, and more particularly to nonvolatile memory modules and/or electronic devices including the nonvolatile memory module.
2. Description of the Related Art
Semiconductor memory devices for storing data may be classified into, for example, volatile memory devices and nonvolatile memory devices. The volatile memory devices are typically configured to store data by charging or discharging capacitors in memory cells, and are widely used as main memories of various apparatuses. The volatile memory devices such as Dynamic Random Access Memory (DRAM) and Static Random Access Memory (SRAM) retain stored data while power is supplied and lose the stored data when power is off.
The non-volatile memory devices such as flash memory devices may maintain stored data even though power is off, and are widely used for storing program codes and/or data in computers, mobile devices, etc.
According to demands for higher memory capacity, faster operation speed and lower power consumption of the memory devices, new memory devices of various types have been developed to realize high integration density of DRAM, fast speed of SRAM and non-volatility of flash memory in a single memory device. For example, Phase Change Random Access Memory (PRAM) using phase change materials, Resistance Random Access Memory (RRAM) using materials having variable resistance such as transition-metal oxides, and Magnetic Random Access Memory (MRAM) using ferromagnetism materials have been receiving attention as memory devices of next generation. The materials constituting the next generation memory devices have some characteristics in common. For example, resistances of such materials vary depending on magnitude and/or direction of applied voltage and/or current. The resistances of such materials can be maintained (meaning non-volatility) even when the applied voltage and/or current is cut off, and thus a refresh operation may not be used for the memory formed based on such materials.
Each memory cell of the resistive memory devices may be formed with one resistive element and one switching element so that data may be stored by controlling voltage and/or current of a bit line and a word line to change resistance of the resistive element.
Due to the advantages of the resistive memory devices, the resistive memory devices have been widely considered in various apparatuses.